OK, "house" /haʊs/, but "houses" /ˈhaʊzɪz/ Source

Why does "s" changes to "z"? I thought it should be /ˈhaʊsɪz/.

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    This leads into one of my all-time favorite lines from The Grinch Who Stole Christmas: "And the one speck of food that he left in the house was a crumb that was even too small for a mouse. Then he did the same thing to the other Whos' houses: leaving crumbs much too small for the other Whos' mouses!" Boris Karloff did a great job as narrator, pronouncing the last word as /maʊzɪz/ to rhyme with /haʊzɪz/. Dr. Seuss enjoyed playing with the language. Oct 22 '15 at 4:16
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    I think the pronunciation /'hausiz// is much more difficult..
    – rogermue
    Oct 22 '15 at 4:33

I've heard both used, with /ˈhaʊsɪz/ usually in a more formal context or when speaking more slowly. I imagine /ˈhaʊzɪz/ is just assimilation of the voicing when the speaker isn't thinking about it, like the /j/ in "don't you" assimilating toward the /t/ and becoming /ʃ/ in casual conversation ("donchoo").

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    Weird, the one with /s/ seems less formal to me (it's a regularization of an irregular plural). Just like how I'd only expect forms like "knifes" to turn up in spontaneous speech, and "knives" to always be used in formal speech.
    – herisson
    Oct 22 '15 at 4:56
  • @sumelic Huh, you're right. I don't know why /s/ feels more formal here, except that it just does. Might be a dialect thing?
    – Draconis
    Oct 22 '15 at 5:54
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    I never heard /ˈhaʊsɪz/ until I moved to New England. But it's quite common here. The /z/ doesn't have anything to do with assimilation; it's just an irregularly pronounced plural. Otherwise, people would say blouzes and spouzes, which they don't. In most of the English-speaking world, the plural is pronounced /ˈhaʊzɪz/, and /ˈhaʊsɪz/ is just plain wrong. Oct 29 '15 at 3:13
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    @PeterShor Hmm... I checked, because I can say both versions without difficulty, and on M&W both pronunciations are given: ...plural hous·es \ˈhau̇-zəz also -səz\...
    – Mari-Lou A
    Dec 15 '15 at 9:52
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    @Mari-Lou: In the UK dictionaries that I've checked, the only version given is /ˈhaʊzɪz/. And while it's common in New England, it must be quite uncommon in California and the New York area, because it sounded rather strange when I first got to Boston. So the right version to teach people learning English is clearly /ˈhaʊzɪz/ (which most people use even in New England). Dec 15 '15 at 11:40

The /z/ in /ˈhaʊzɪz/ was caused by voicing assimilation, which historically applied in a fairly automatic way to fricative sounds in English. The sound [z] is the voiced counterpart of [s], and in Old English, an /s/ in the middle of a word was pronounced as voiced [z] when it came between vowels—which are voiced sounds. (There were some complications related to prefixed and compound words.)

We can see the effect of the Old English rule of voicing assimilation for fricative consonants in some other words where a final voiceless fricative in the singular changes to a voiced fricative in the plural. A few examples: leaf-leaves, wolf-wolves, and for some speakers path-paths, truth-truths. (From an etymological perspective, the final consonant of leaf was actually "originally" voiced in Proto-Germanic, but devoiced in Old English because it was in word-final position. But the resulting distribution of voiced and voiceless forms is the same as for words like house and path whose fricatives come from Proto-Germanic voiceless sounds.)

But as Peter Shor noted in a comment, this process is not automatic in modern English, and in fact the general pattern now is that voiceless fricatives between vowels do not assimilate in voicing; they stay unvoiced (as in the words blouses and spouses, for speakers who pronounce the singular forms of these words with voiceless /s/).

So the plural form of house has become irregular in pronunciation.

Here's a related question: Pronunciation: ‘lousy’ vs. ‘mousy’. Why?


This is strange. I grew up in Boston+NY and have always said "houZes". I first noticed people pronouncing it 'houSes" several years ago on TV (I now live in Europe). Since then I keep hearing it in this unvoiced form! I thought it was a California thing, or maybe a generational shift.

And now the other day when I was watching Silicon Valley I thought they were using the unvoiced S in surprising places for example saying "pleaSe" rather than "pleaZe".

I wonder if the S vs. Z sounds less assertive and is being used to sound less confrontational in these "woke" times, like perhaps people are forming statements as questions with rising intonations ("uptalk") but that is pure speculation. Have to keep an eye on thiS....

  • With regard to "houZes" and "houSes," I imagine that you actually have in mind "houZez" and "houSez"—no?
    – Sven Yargs
    Nov 2 '17 at 3:20
  • That's a good point Sven. I would pronounce it houzez but not sure if someone not aspirating the first s would then aspirate the final s. Will have to listen more closely. I'm imagining maybe they'd only lightly aspirate it?
    – David C
    Nov 2 '17 at 5:05

I say blouses and spouses with a /z/, but that's because the singular also is pronounced /z/ in many varieties of English. I pronounce house with an /s/ and houses with a /z/, and of course the verb form "to house" I pronounce with a /z/.

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    How does this answer the question of why this occurs?
    – tchrist
    Nov 7 '17 at 4:51

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